Stimulator



FIG. 1 is a perspective view of a stimulator;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a rear elevational view thereof.

The broken lines are included for the purpose of illustrating portions of the stimulator that form no part of the claimed design. 

The ornamental design for a stimulator, as shown and described. 